Transmitter Considerations for 5G Wireless Powered Sensor Networks

Novel Technologies towards the Implementation and Exploitation of “Green” Wireless Agriculture Sensors

“…The experiments indicated that using high-gain antennas can significantly increase the charging and the reading distances and can also support the simultaneous charging of several wireless sensor platforms with the Energy Harvesting feature. This observation led to the design of a UAV-carried beam-forming array which can direct the maximum gain of the radiation beam in five different pre-determined directions along two perpendicular planes [ 22 ]. The concept idea and a prototype conformal cross-shaped array designed for the ISM band at 2.4 GHz are presented in Figure 16 .…”

“…For the three radiating elements in each of the two 3 × 1 arrays, the power ratios at 1:2:1 and the phase difference of the three adjacent driving currents can be either 0° or +120° or −120°. The power ratio is accomplished using the power divider presented in Figure 17 a, which is a combination of three 3 dB Wilkinson dividers [ 22 ] arranged so they can have one input port and three output ports. The central port is directed on the central (common) patch element.…”

“…The 1:2:1 power divider is followed by a three-stage phase shifter. The phase shifter is implemented using two different electric paths per branch, which are selected in combination with using three pairs of single-pole double-through (SPDT) switches [ 22 ]. The phase shifter schematic in Figure 15 shows the case when the three patch radiators are fed with 120° phase difference, causing the directivity of the 3 × 1 elements array to form a −37° angle.…”